The Country Music Hall of Fame and Museum is about to reveal the final pieces of its size-doubling 210,000-square-foot expansion on April 15, and the Nashville institution will celebrate the occasion with a free outdoor concert.

Vince Gill, Ricky Skaggs, Lee Ann Womack and Buddy Miller are among the country favorites set to perform that afternoon on an outdoor stage located at 5th Ave S. and Demonbreun. The free concert will start at 1:15 p.m. on Tue., April 15.

The Museum is opening 10,000 square feet of new exhibit space, including the interactive joint “ACM Gallery” and “Fred and Dinah Gretsch Family Gallery,” and “Design Gallery: A Window into the Collection,” which gives guests a behind-the-scenes peek at the Museum’s vast archive.

Speaking of the Hall of Fame and all-star concerts, tickets for this year’s “All 4 The Hall” benefit concert at Bridgestone Arena are on sale at 10 a.m. Fri., April 4 at Ticketmaster outlets, at www.ticketmaster.com, by calling 1-800-745-3000 and at the Bridgestone Arena box office. Performers include Gill, Keith Urban, Carrie Underwood and Reba McEntire.